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Persistent and periodic northerly low‐level jets have been identified in the South Asian mid‐latitudes and subtropics, which are modified by the presence of Makran mountain ranges adjacent to the central south coast of Pakistan, where they blow predominantly in the west‐northwest to northeast directions. These winds lead to the generation of a new wave system and propagate through the Arabian Sea as “makran swells”. They are prevalent during October to May. The measurements along the west coast of India reveal systematic variations in the wave spectra relating the makran events. This has been further verified through the WaveWatch III simulations forced by the CFSR winds. The significant wave heights up to 4.5 m were hindcasted in the northern Arabian Sea during these events. Once generated, the makran swells propagate to the eastern Arabian Sea and western Arabian Sea with directional sectors of 300–360° and 0–60°, respectively. The characteristic features and the spatial extension of the makran swells are particularly analysed.

The Kayamkulam-Arattupuzha coastal stretch which forms part of the Kayamkulam-Thottapally (Quilon-Cochin) sector of the Kerala coast of India has been an eroding coastline for the past two to three decades. From 2000 to 2007 there has been a drastic increase in the erosion particularly around the inlet. Coincidentally, during the same period, two long breakwaters were constructed for the formation of the Kayamkulam fishing harbour. A critical analysis of the field data clearly indicates that the morphological changes are directly due to the construction of breakwaters. This paper reports the application of numerical models as an effective tool to study the coastal dynamics of the area and also to quantify and assess the shoreline changes for predicting the shoreline evolution pattern over a period of time. The Spectral Wave (SW) and Hydrodynamic Flow Model (FM) of the MIKE 21 modeling system (DHI) have been used for modeling the coastal dynamics, whereas, the studies on the shoreline change were carried out using LITPACK coastal suite (DHI). The paper highlights the need for an integrated coastal management approach as a proactive measure wherein shoreline management plans are also developed and implemented along with the execution of the project to address adverse impacts if any.

Wind waves in the innershelf of the south-central Kerala coast, south-west India were measured at four locations during different seasons. Simultaneously, numerical models were developed to simulate the wave and sediment transport regime of the innershelf. Strong monsoonal influence is seen in the wave characteristics with greater amplitudes, lower periods and switch-over from SW to SWW-W direction. The net annual longshore sediment transport is southerly in the innershelf and northerly in the surf zone. These counter-directional transports are linked by seasonally reversing the cross-shore transports. In the locations where the transports in the longshore and cross-shore directions are balanced, stable beaches prevail. Erosion/accretion tendency prevails in locations where these transports are not balanced. The southern and northern parts of the coast where onshore transports are predominant could be accreting zones. The erosion/accretion pattern deduced from the sediment transport model corresponds well with the long-term erosion/ accretion trend for this coast.

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